Car owners appreciate more and more being able to have a rear seat which can be folded so as to provide a useful space as an extension of the boot, and equally being able to convert the seats into a couchette, for example, for travelling at night. Obtaining a couchette in an automobile vehicle is at present the result of tipping the back-rest of one of the front seats towards the rear seat, which considerably reduces the space remaining available and, furthermore, requires particular arrangements for controlling the tipping of the back-rest of the front seat and the folding of the rear seat when it is desired to have both possibilities available.